Manufacture of tubes



ou. 4, 1932. F. R. BONTE 1,881,069

MANUFACTURE 0F TUBES Filed 4 July 20. 1929 \V////////////////////////////////l///////////////l/////////// INVENTOR MKM .Amy 546mg,

Patented 1932 Uma STATES FREDERICK B. BONTE. F BEAVER FALLS, PENNSYLVANIA Hamac'ruan or mns Application alec my a0, 1929. serial Nofsvavao.

The present invention relates to a process for producing tubes which is particularly aB- 16 plicable to the production of thin gau e tu ing and by means of which the manu acture of thin gauge tubing can be Vcarried out economical y and in large quantity with existing types of machinery, and it constitutes an im- 20 provement on the invention shown in my Patent No. 1,527 ,7 80,-dated February 24, 1925. The invention may be readily illustrated in connection with the accompanying drawing in which Figure 1 represents an assembly of nested tubular members on a central core;

Fil re '2 represents the nest of vtubular mem rs after it has been rolled; and

Figure 3 illustrates the assembly after still $0 further rolling.

In carrying out the invention, a lurality of tubular steel billets are formed o varying diameters, these billets being arranged in sets, so that one nest will be received within anu other. This is illustrated in Fi re 1 wherein l 2 designates a solid core on which is a hollow billet 3. Enclosing the hollow billet 3 is another billet 4, and this in turn is enclosed by another billet 5. Two or more of the billets 40 may comprise a nest, more than two preferably being used. The wall thickness of the billets maybe uniform, as shown in Figure 1, l or may be non-uniform according to whether it is desired to produce tubes having uniform gauge thickness or having varying gauge thickness. There is a slight clearance between the billets, and a slight clearance between the inside of the billet 3 and the core 2.

i The billets may be manufactured according to any well-known or preferred process, and

vthe unit through the reducing rolls and tubes "5 after being formed are preferably ickled and then limed, as disclosed in my said atent 1,527,780. In nesting the billets and in inserting the core 2, a filler of a compound adapted to prevent the weldinff of the billets to each other and of the inner illet to the core is provided in the spaces between the respective elements of the assembly. This lubricating material must be one that will resist high temperatures and which will not scratch the sur- 60 face of the metal in the processl of forming the tubes. I have found that dry graphite provides the bestr lubricant for this purpose. In Ftigure 1 the layers of graphite are indicated a Afterthe billets have been nested and assembled about the core 2, they ma be connected together by means of a pin assing through them and through thecore, a thou h the use of this pin is not essential. After t e 7o assembly has -been completed, it is placed in a furnace and heated almost to a welding temperature. It is then passed through reducing rolls. I have found that in passing will all be elongated to substantially the same extent. This is illustrated in Figure 2 wherein 2 designates the core and 3', 4 and 5' are the partially completed tubes formed by the billetsv 3, 4 and 5, respectively. It 8o will also be noted that the core 2 is elongated to the 'same extent as the billets. -If in the process of rolling the diameter of the outer billetis reduced one-half, the tubes willv be elongated practically twice the original length- By further rolling of the assembly, the tubescan be reduced to the desired diameter andthe desired wall thickness. In Figure 3 I'have shown the assembly further reduced and vproviding a nested series of thin wall seamless tubes 3", 4 and 5" still supported on the core 2. The graphite which is interposed between the various elements of the assembly prevents the metal from stickin and welding and provides a lubricant w ich facilitates the separation of the tubes. After the assembly has'been rolled to the desired extent, the tubes are separated by removin one from the other. I have found that t e separation is facilitated and that limproved tube-s are formed by making the core 2 longer than'the billets. B making the core 2 longer than the. billets, t e rojecting end of the core forms a guide a ut which the tubes are supported as they are elon ated. Since the bar cr core elongates to su stantially the same extent as the billets, one `end'oi the core at least will always project beyond the ends of the tubes, and this the separation ofthe tubes. By connecting the billets together at one core can be grasped or clamped in effecting `end by the use of the pin 7, the elongation is .billets are all of confined in one direction. This makes the diameters will not be of uniform gauge.l

This feature lends iiexibility to the invention, in that it allows for the production odiierent gauge tubes in the diameters at which tubes of a particular gauge are required.

While I have indicated the billets and cores a-s being circular, the invention is not confined to the manufacture of round tubing,

- andthe core and billets may be of any predrawing die over a mandrel by ferred cross-sectional shape. After the.

tubes have been rolled and they are se arated, they are'preferably drawn throng a means of which a smooth finish can be attained and the cross sectional shape of the tube modied if it is desired to change the cross sectional shape.

As a modification of the invention, it may be practiced on welded steel tubin particularly electrically welded steel tu ing, and eliminate certain defects which at the present time .prevent the use of welded steel tubin in the aeroplate industry. In the welding o steel tubing, the portion ofthe metal along theV seam 1s heated to a temperature, considerably above the temperature of the body .fthltb.. Y o e u mg Thls locallzed heatmgcauses' the core together at one end of the assembly,

and then rolling the reducing the billetsv a grain growth along the seam in the region of the weld, which weakens the tubing.

By practicing the present invention on welded tubes, the welded tubes are heated and then are rolled .and the combined. action of the heating and the rolling corrects the grain structure along the seam of the tube and makes the metal of the tube substantially uniform andr homogeneous throughout. A y It willbe understood that I have described preferred ways of carrying out my invention,

l. but that various changes and modifications may be made therein within the contemplaheating tion of my invention and under the scope of the following claims.

I claim 1. In the method of s forming seamless tubes, which comprises nesting a plurality of billets about La. core with the ends of the billets at one end of the assembly in the same vertical plane, securing the other ends of the billets toeach other and to the mandrel, heating the assembly, and simultaneously elongating all of the billets to substantially the same extent in la progressive manner from the secured ends.

2. The method of simultaneously forming a. plurality of seamless tubes of diierent'diameters and of equal wall thickness, which comprises nesting a plurality-of hollow bi1- letsabout a core, with the ends of the bi1- lets at one end of. the assembly in the same vertical plane, securin 4the other ends of the billets to each other an ing' the. billets and core, and then rollin the assembly from the secured ends toward the other ends to elongate the billets and the core, and thereafter separating the resulting tubes.

3. The method of manufacturing a plurality of seamless tubes, which comprises nestin :a -plurality of hollow billets about la core o greater length than the billets with the ends of the billets at one end of the assembly in the same vertical plane, securing the other ends of the billets to each other and to the end ofthe mandrel,vheating the assembly from the end of the mandrel to which the billets are secured toward the other ends of the billets, and rollin the assembly to elongate the respective bil ets and the core to substantially the same extent, thereby producing a plurality of concentric tubes, and thereafter separating the tubes. f

to the mandrel heat- 4. The method of manufacturing a plurality of 'seamless tubes of diii'erent diameters,

which' comprises' nesting a plurality of'concentric billets about a central core, introducing a lubricating loose non-metallic 'material between the concentric. billets and be-. tween the innermost billet and the core for.

preventing the billets from welding together and preventing the innermost b11let from welding to the core, securing the' billets and the assembl assemb y and thereb to form a plurality o! concentric tubes.

5. The method of manufacturing a pluralit of seamless tubes of dilerentdiameters, Y

w ich comprises nesting a plurality of concentric billets about a vcentral core, introduc.-

ing'a lubricating loose iaky nonv metallic material between the concentric billets and between the innermost billet and the core for preventing the billets from weldin together and .preventing the innermost b let from welding to the core, securing the billets and lo ing a plurality of seamless tubes o the coreftogether against relative lon 'tudivnal movement at one end of the assem ly by a connector passing therethrough, heating the l assembly, and then rolling the assembly and thereby reducing the billets to form a plurality of concentric tubes, the core being lon er than the billets and being elongated to su stantially-the same extent as the billets;

6. The' method of simultaneouslg7 producdifferent diameters, which comprises nesting a plurality of hollow billets of equal length about a core which extends entirely through the innermost billet and projects beyond one end thereof,pass'ing a pin through the other end of the billets and the core for holding the billets and the core against elongation in one direction, heating the assembl and thereafter rolling the assemblyuntil the conceni 20" tric billets are reducedlto a series of concentric tubes and the core is reduced to a rod, and thereafter separating'the tubes and removing the rod. r 7 In the process of manufacture'of steel tubin the `ste s which comprise nesting a plura ity of tu ular elements about a core, heating the assembly, and then rollin the assembly while hot to elongate the tu ular elements and produce a concentric series'of t tubes and while'holding the leading ends of .the tn bes ofthe assembly against relative longitudlnal movement in either direction. v

In testimony whereof I havehereunto set myI hand.

- FREDERICK R. BONTE. 

